Groups 1A through 8A are called representative elements because the display a wide range of physical and chemical properties.
Elements that are in the same group have the same number of valence electrons
The valence electrons of representative elements are in s or p orbital.
The elements that are in the same group may have the same number of valence electrons but they are not identical because they have different number of nonvalence electrons.
As a new level of electrons is added the atomic radius increases. Then the ionization energy decreases.
A lower ionization energy makes it easier to loose electrons.
Metals tend to loose ions. But the lower the ionization energy, the more reactive the metal.
The groups of metals reactivity increases as the atomic number increases. The opposite is true for nonmetal
--diagonal relationships:
Hydrogen:
Placed in group 1A—one valence electron
Metallic and nonmetallic
Discovered by Henry Cavendish in 1766
Used to be called “flammable air”
Universe contains 90% of hydrogen mass
Isotopes: protium, deuterium, tritium
-protium is vast majority(99.985%) ---no neutrons -Deuterium is 0.015%--1 neutron -Tritium is radioactive-2 neutrons
· the physical properties of isotopes differ slightly because of differences in atomic mass.
· heavy water slows down the neutrons produced during nuclear fission so that they can be absorbed by the uranium fuel.
· when a hydrogen atom acts like a nonmetal, it gains an electron and achieves the stable electron configuration of helium.
· when hydrogen reacts with a nonmetal, it acts like a metal.
· hydrogen loses its single electron and forms a hydrogen ion.
· a hydrogen ion is a nucleus with a single proton.
· hydrogen can be produced when a metal reacts with an acid or when electricity is used to seperate water.
· large quantities of industrial hydrogen are produced when water reacts with methane.
· methane is the main ingredient in natural gas.
· hydrogen is also used to convert liquid vegetable oils into solid fats such as shortening.
Section 7.1 Group 1A: Alkali Metals *The term alkali comes from the Arabic al-quili meaning “ashes of the saltwort plant.” Saltworts grow on beaches or near salt marches. Group 1 Metals react with water to form alkaline solutions so they are called alkali metals. LITHIUM:Lithium is the lightest alkali metal. They are found in water, soil, and rocks. Lithium has an atomic radius of 152 pm and an ionic radius of 76 pm. Long-lasting lithium batteries may extend the range of electric automobiles. Lithium carbonate is used to strengthen glass and as a drug to treat bipolar disorders. Such disorders involve mood swings from mania to depression. SODIUM AND POTASSIUM:Sodium and potassium are the most abundant alkali metals. Sodium is used in sodium vapor lamps and as a heat exchanger in nuclear reactors. Because potassium is more reactive than sodium and more expensive to produce, elemental potassium has fewer industrial uses. Potassium ions are the most positive ions within cells. Sodium ions are the most common positive ions in the fluid that surrounds cells. Potassium chloride serves as a salt substitute for people whose intake of sodium must be limited. Potassium compound are include in fertilizers because potassium is an important factor for plant growth and development. OTHER ALKALI METALS:The most reactive alkali metals-rubidium, cesium, and francium-have little commercial use. Rubidium, with a melting point of only 40degreesC, melts on a hot day. It will burst into flames if exposed to air. Francium, the most reactive alkali metal, is a rare radioactive element.
Group 2A: Alkaline Earth Metals
· Group 2A elements form compounds with oxygen called oxides
· Oxides produce alkaline solutions when they react with water
· Alkaline earth metals are shiny solids that are harder than alkali metals
· Alkaline earth metals are usually found combined with oxygen and other nonmetals in Earth’s crust
· When exposed to oxygen, they form a thin oxide coating
Beryllium
Lightest member of Group 2A
Is found combined with aluminum, silicon, and oxygen in a material called beryl
Used to moderate neutrons in nuclear reactors
Tools made from an alloy of beryllium and copper are used in situations where a spark from steel tools touching steel equipment could cause a fire or explosion
Calcium
Essential element for humans in maintaining healthy bones and teeth
Mainly combined with carbon and oxygen in calcium carbonate
Main ingredient in rocks such as limestone, chalk, and marble
When calcium carbonate decomposes, it forms oxide of calcium called lime
Magnesium
· Abundant element, formed into almost any shape
· Alloy of magnesium with aluminum and zinc are lighter than steel but just as strong
· Bike frames and “mag” wheels are made of magnesium
· The oxide of magnesium has such a high boiling point it is used to line furnaces
· Plants can’t function without it (chlorophyll)
· Plays key role in muscle function and metabolism
· Hard water = lots of magnesium and calcium ions
· Water softness exchange sodium or hydrogen ions for the calcium and magnesium ions
A) Arsenic, Antimony, and Bismuth (Group 5A)
· Group 5A
· Among the oldest know elements
· Arsenic is used for some illnesses
· Antimony used for common cosmetics (darkening eyebrows)
· Bismuth used as remedy for diarrhea and nausea
B) The Oxygen Group (Group 6A)
· Have 6 valence electrons and act mainly as nonmetals
· Tend to gain two electrons to form ions with a 2- charge 1)Oxygen:
· Joseph Priestley (1733-1804) is credited for the discovery of oxygen
· Oxygen has two allotropes (allotropes: Forms of an element with different structures and properties when they are in the same state-solid, liquid, or gas)
· Oxygen is separated from the other gases in air through a distillation process that is based on difference in boiling point among the gases
· Oxygen is the most abundant element in Earth’s crust 2)Sulfur:
· Found in underground deposits
· Has 10 allotropes
· Reacts with oxygen when burned in air to form sulfur dioxide, which is used to preserve fruit and as an antibacterial agent
· More than 90% of the sulfur dioxide produce is use to make sulfuric acid
· Heat and hydrogen sulfide released to deep ocean vents support many organisms 3)Selenium:
· Selenium can be found in suck foods as fish, eggs, and grains
· Selenium works with vitamin E to prevent cell damage
· Selenium can convert light into energy, so it can be used for solar panels
8A: Noble gases
Were among the last naturally occurring elements to be discovered
They are colorless and un-reactive
In 1962 the inorganic chemist Neil Bartlett created compounds from xenon and fluorine, when no one thought it was possible
They have a maximum number of 8 electrons in their outermost energy levels
They usually don’t react because of their stable electron configuration
There are no known compounds of helium, neon, or argon
Helium
The lightest noble gas
Discovered in the emission spectrum of the sun
Can be found on earth in natural-gas wells
Used in airships, blimps, and balloons
A mixture of helium and water are used by deep sea divers
Liquid helium is used as a coolant for superconducting magnets
Neon
Neon is used in light displays, known as neon lights
The color of neon lights is not a constant because gases other than neon can be used in displays
For example- argon emits blue light and helium emits pale yellow light
Argon and krypton
Argon is the most abundant of the noble gases on earth, it makes up 1% of earths atmosphere
Argon provides an inert atmosphere for procedures such as high-temperature welding.
This avoids the dangerous mixture of electrical sparks, heat and oxygen.
Argon and krypton are used to prolong the life of filaments in incandescent light bulbs and as a layer of insulation between panes of glass
7.3
Long-lasting lithium batteries may extend the ranger of electric automobiles. Compounds of lithium are used in dehumidifiers to absorb water. Lithium carbonate is used to strengthen glass and as a drug to treat bipolar disorders.
Alloys of lithium, magnesium, and aluminum are used for items such as airplane parts because these parts must be strong, yet lightweight. Alloy is used as a solid solution. A chemist can fine-tune the properties of an alloy by varying the amount of each element.
Sodium and Potassium
The most abundant alkali metals
Potassium is more reactive than sodium and more expensive to produce.
Humans and other vertebrates must have sodium and potassium in their diets because many biological functions are controlled by sodium and potassium ions.
When a nerve cell is stimulated, sodium flows in and potassium flows out. This flow of ions across the cell membrane carries the nerve impulse along the cell. After the impulse passes, a compound attached to the cell membrane uses energy to move the ions back across the membrane so that they are in position for the next impulse.
Other Alkali Metals
The most reactive alkali metals-rubidium, cesium, and francium-have little commercial use.
· Share properties such as electrical conductivity, luster, and malleability with other metals
· Little variation in atomic size, electronegativity, and ionization energy across period
· There are differences in properties, especially physical
· Physical properties determined by electron configuration
· Most transition metals are hard solids, with high melting points and boiling points
· Differences in properties based on ability of unpaired d electrons to move up into the next valence level
· More unpaired electrons in d sublevel the greater the hardness and higher melting points and boiling points of metal
Formation of Ions
· An ion is formed when an atom loses or gains an electron
· Losing electrons results in a positive charge
· Gaining electrons results in a negative charge
· Positive ions can have a charge of up to 6+
· Most compounds of transition metals have colour.
o The metal ions in these compounds have partially filled d sublevels
o Electrons in these sublevels can absorb visible light of specific wavelengths
o Exceptions are white compounds that contain scandium, titanium, or zinc
o Scandium and titanium ions have empty d sublevels
o Zinc ion has a completely filled and stable d sublevel
o Electrons in these three ions can be excited to higher levels, but not by visible light
o These compounds respond to wavelengths in the ultraviolet range
· If a transition metal can form more than one type of ion, a change from one to another can often be detected by a colour change
Sources of Transition Metals
Copper, silver, gold, platinum, and palladium are the only transition metals that are unreactive enough to be found, pure, in nature.
The rest of the transition metals are found in nature combined with nonmetals, usually in oxides, sulfides, or with other minerals in ores.
Copper, as it is found in nature. Metallurgy is the branch of science that works with extracting metals from ores.
There are three groups of methods for metallurgy:
· Those that use high temperatures
· Those that use solutions
· Those that use electricity
Many countries’ economies rely on their source of transition metals. Places with an abundance of useful transition metals include Canada, Zaire, Democratic Republic of the Congo, and South Africa.
Magnetism & Metals:
· Magnetism is the ability of a substance to be affected by a magnetic field. A moving electron creates a magnetic field.
o Because paired electrons spin in opposite directions, their magnetic fields tend to cancel out. When all electrons in an atoms or ions are paired with another electron, the substance is slightly affected, if affected at all.
This property is called diamagnetism.
o When there is an unpaired electron in the valence orbital of an atom or ion, the electron is attracted to a magnetic field.
§ This property is called paramagnetism.
o Most substances act as temporary magnets: meaning their magnetic properties disappear after the magnetic field is removed.
o Transition Metals iron, cobalt, and nickel have a property called ferromagnetism. Ferromagnetism is the strong attraction of a substance to a magnetic field. The ions align themselves in the direction of the field. When the field is removed, the ions stay aligned and the metals continue to act as a magnet. Thus, iron, cobalt, and nickel can form permanent magnets.
Uses of Transition Metals
· Copper is used in electrical wiring.
· Zinc is used as protective coating for other metals.
· Iron is used in making steel.
· Many are found in alloys which are used to make things such as engines, drill bits, surgical instruments, and armor.
· Plastics, petroleum, and food industries use transition metals such as platinum, palladium, and nickel to control the conditions at which a reaction will occur.
· Our bodies need large amounts of some elements to function: carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, sodium, potassium, calcium, magnesium, and chlorine. There are other essential elements, but only in small amounts.
· Except for scandium and titanium, all period 4 transition metals play vital roles in organisms.
· Iron (ions), Manganese, copper, and cobalt all help in some way with cells.
Halogens (Group 7A) Halogens are a series of nonmetal elements from group 17 on the periodic table. This group includes flourine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). There is also a “undiscovered” element (ununseptium) that might also be a halogen. Halogens are highly reactive. In sufficient amounts, they can be harmful/lethal to biological organisms. The reason why they are so highly reactive is because their atoms outer shells are one atom short of 8 electrons. Through reacting with other elements they can gain the electron that they need to have a full 8. Bromine and chlorine are used as disinfectants to kill bacteria and other harmful microorganisms. If you were to fall and scrape your knee and need to clean it off, that’s what you would really be using. They are also used to disinfect our drinking water, swimming pools, dishes, and surfaces. Chlorine is used to bleach paper products andfabrics.
-Named for their ability to form compounds with almost all metals.
-Because these compounds are called salts, the elements are called “salt formers” or halogens.
-Halogens differ in their physical properties.
-Chemical behavior is similar with only one exception. Astatine is a radioactive element with no known uses.
-The elements share the following general properties:
-reactive non-metals
-always found combined with other elements in nature
-have 7 valence electrons
-generally forms ions with a 1- charge
Fluorine
-Halogen with the lowest atomic number, so it has a small atom that provides little shielding of its valence electrons from the nucleus.
-Most electronegative element on the periodic table. It has the greatest tendency to attract electrons. Also the most active element
-Reacts with every element except helium, neon, and argon.
-The mineral fluorite, which contains fluoride and calcium, is used to lower the melting points of other minerals to make it easier to separate them from their ores.
-Fluorine compounds are added to toothpaste and drinking water to protect tooth enamel from decay.
-A compound of fluorine and carbon provides a non-stick coating on pots and pans.
Chlorine
-Reacts with nearly all elements.
-Chlorine is a deadly gas, but it has many uses, some which save lives.
-Chlorine compounds are used as bleaching agents by textile and paper industries.
-Hydrochloric acid in your stomach helps digest food.
Bromine and Iodine
-Few commercial uses for their compounds.
-Your body needs iodine to maintain a healthy thyroid gland. This gland produces hormones the control growth and your metabolic rate.
-Seafood is a good source of iodine.
-Campers use iodine to disinfect water.
There are five known halogens bromine, idodine, chlorine, flourine, and astatine. Halogens are non-metallic elements found in group 17. They are highly reactive, and only found as compounds or ions.
At room temperature fluorine and chlorine are gases, bromine is a liquid and iodine and astatine are solids.
Noble Gases
Among the last naturally occurring elements to be discovered because they are colorless and unreactive.
Known for their stability
Have maximum number of electrons in their outermost energy level.
Helium
Lightest Noble Gas.
Found on earth in natural gas wells.
Used in blimps, airships, and balloons.
Liquid helium is used as a coolant for superconducting magnets.
Neon
Used in light displays that are commonly referred to as neon lights
Color of neon lights is not constant because gases other than neon can be used in the displays.
Argon and Krypton
Argon is most abundant of the noble gases on Earth, makes up about 1% of Earth’s atmosphere.
Provides an inert atmosphere for procedures such as high-temperature welding.
Both used to prolong the life of filaments in incandescent light bulbs and as a layer of insulation between panels of gas.
Inner Transition Metals
Lanthanide Series
Silvery Metals
High Melting Points
Very little variation between two elements in the series they are found mixed together and are very hard to separate.
Actinide Series
Radioactive elements
Only three exist in nature, the rest are synthetic elements called transuranium elements, an element with an atomic number greater that 92.
Transuranium elements are created in partial accelerators or nuclear reactor.
Most decay quickly; one exception is plutonium-239 that can stay radioactive for thousands of years.
Group 3A:The Boron Group
*Group 3A elements are always found combined with other elements in nature
*Most often found as oxides in Earth's crust
*Group 3A contains one metalloid (boron), one metal (aluminum), and three rare metals (gallium, indium, and thallium) Boron
+Boronis one of the seven micronutrients essential to allplant growth
+used in reactor control rods +melting point: 205°C+Main Source of Boron is a complex compound of boron called "borax"
+Half of the world's supply of borax comes from a large deposit in California's Mojabe Desert.
+Borax is used as a cleaning agent and as fireproof insulation
+Boric acid is another compound of boron and is used as a disinfectant and as an eye wash
+Boron Nitride is the second hardest known material
Aluminum
+Aluminumis the most abundant metal and third most abundant resource in the earth's crust
+Aluminum oxideis the major compund inbauxite
+ The compud aluminum sulfate, known as alum, is used in antiperspirants and to remove supended particles during water purification
Gallium
+Gallium is used in somethermometersbecauseit remains aliquidover a wide temperature range :30°C to 2403 °C + A compound ofgallium and arseniccalledgallium arsenideproduces andelectric currentwhen it absorbs light
Group 2A: Alkaline Earth Metals
· Group 2A elements form compounds with oxygen called oxides
· Oxides produce alkaline solutions when they react with water
· Alkaline earth metals are shiny solids that are harder than alkali metals
· Alkaline earth metals are usually found combined with oxygen and other nonmetals in Earth’s crust
· When exposed to oxygen, they form a thin oxide coating
Beryllium
Lightest member of Group 2A
Is found combined with aluminum, silicon, and oxygen in a material called beryl
Used to moderate neutrons in nuclear reactors
Tools made from an alloy of beryllium and copper are used in situations where a spark from steel tools touching steel equipment could cause a fire or explosion
Calcium
Essential element for humans in maintaining healthy bones and teeth
Mainly combined with carbon and oxygen in calcium carbonate
Main ingredient in rocks such as limestone, chalk, and marble
When calcium carbonate decomposes, it forms oxide of calcium called lime
Magnesium
· Abundant element, formed into almost any shape
· Alloy of magnesium with aluminum and zinc are lighter than steel but just as strong
· Bike frames and “mag” wheels are made of magnesium
· The oxide of magnesium has such a high boiling point it is used to line furnaces
· Plants can’t function without it (chlorophyll)
· Plays key role in muscle function and metabolism
· Hard water = lots of magnesium and calcium ions
· Water softness exchange sodium or hydrogen ions for the calcium and magnesium ions
7.3 Properties of d-Block and f-Block Elements
Vocabulary
Lanthanide series- The f-block elements that form period 6. Actinide series- The f-block elements from period 7 that follow the element actinium. Ferromagnetism- The strong attraction of a substance to a magnetic field. Metallurgy- The branch of applied science that studies and designs methods for extracting metal and their compounds from ores. Magnetism- The ability of a substance to be affected by a magnetic field. Diamagnetism- When electrons repel or are unaffected by a magnetic field. Paramagnetism- When an electron is attracted to a magnetic field
• Transitional metals vary in atomic size, electro-negativity and ionization across the period. Although they share like qualities, they have many differences in properties, such as structure and strength.
• Differences in properties are among transition metals are based on the ability of unpaired d electrons to move into the valence level.
• The D- block transition metals and f-block inner transition metals are more similar across a period than are the s-block and p-block elements
• The more unpaired electrons in the d-sublevel, the harder the transition metal and the higher its melting point and boiling points.
• In ferromagnetic metals, ions are permanently aligned in the direction of a magnetic field.
• Many transition metals are strategic metals.
• Lanthanide are silvery metals with high melting points such as: tinted sun glasses.
• Actinides are radioactive elements such as: americium which is found in smoke detectors.
Representative Elements
- Groups 1A through 8A are called representative elements because the display a wide range of physical and chemical properties.
- Elements that are in the same group have the same number of valence electrons
- The valence electrons of representative elements are in s or p orbital.
- The elements that are in the same group may have the same number of valence electrons but they are not identical because they have different number of nonvalence electrons.
- As a new level of electrons is added the atomic radius increases. Then the ionization energy decreases.
- A lower ionization energy makes it easier to loose electrons.
- Metals tend to loose ions. But the lower the ionization energy, the more reactive the metal.
- The groups of metals reactivity increases as the atomic number increases. The opposite is true for nonmetal
--diagonal relationships:Hydrogen:
- Placed in group 1A—one valence electron
- Metallic and nonmetallic
- Discovered by Henry Cavendish in 1766
- Used to be called “flammable air”
- Universe contains 90% of hydrogen mass
- Isotopes: protium, deuterium, tritium
-protium is vast majority(99.985%) ---no neutrons-Deuterium is 0.015%--1 neutron
-Tritium is radioactive-2 neutrons
· the physical properties of isotopes differ slightly because of differences in atomic mass.
· heavy water slows down the neutrons produced during nuclear fission so that they can be absorbed by the uranium fuel.
· when a hydrogen atom acts like a nonmetal, it gains an electron and achieves the stable electron configuration of helium.
· when hydrogen reacts with a nonmetal, it acts like a metal.
· hydrogen loses its single electron and forms a hydrogen ion.
· a hydrogen ion is a nucleus with a single proton.
· hydrogen can be produced when a metal reacts with an acid or when electricity is used to seperate water.
· large quantities of industrial hydrogen are produced when water reacts with methane.
· methane is the main ingredient in natural gas.
· hydrogen is also used to convert liquid vegetable oils into solid fats such as shortening.
Section 7.1 Group 1A: Alkali Metals
*The term alkali comes from the Arabic al-quili meaning “ashes of the saltwort plant.” Saltworts grow on beaches or near salt marches. Group 1 Metals react with water to form alkaline solutions so they are called alkali metals.
LITHIUM: Lithium is the lightest alkali metal. They are found in water, soil, and rocks. Lithium has an atomic radius of 152 pm and an ionic radius of 76 pm. Long-lasting lithium batteries may extend the range of electric automobiles. Lithium carbonate is used to strengthen glass and as a drug to treat bipolar disorders. Such disorders involve mood swings from mania to depression.
SODIUM AND POTASSIUM: Sodium and potassium are the most abundant alkali metals. Sodium is used in sodium vapor lamps and as a heat exchanger in nuclear reactors. Because potassium is more reactive than sodium and more expensive to produce, elemental potassium has fewer industrial uses. Potassium ions are the most positive ions within cells. Sodium ions are the most common positive ions in the fluid that surrounds cells. Potassium chloride serves as a salt substitute for people whose intake of sodium must be limited. Potassium compound are include in fertilizers because potassium is an important factor for plant growth and development.
OTHER ALKALI METALS: The most reactive alkali metals-rubidium, cesium, and francium-have little commercial use. Rubidium, with a melting point of only 40degreesC, melts on a hot day. It will burst into flames if exposed to air. Francium, the most reactive alkali metal, is a rare radioactive element.
Group 2A: Alkaline Earth Metals
· Group 2A elements form compounds with oxygen called oxides
· Oxides produce alkaline solutions when they react with water
· Alkaline earth metals are shiny solids that are harder than alkali metals
· Alkaline earth metals are usually found combined with oxygen and other nonmetals in Earth’s crust
· When exposed to oxygen, they form a thin oxide coating
Beryllium
- Lightest member of Group 2A
- Is found combined with aluminum, silicon, and oxygen in a material called beryl
- Used to moderate neutrons in nuclear reactors
- Tools made from an alloy of beryllium and copper are used in situations where a spark from steel tools touching steel equipment could cause a fire or explosion
Calcium- Essential element for humans in maintaining healthy bones and teeth
- Mainly combined with carbon and oxygen in calcium carbonate
- Main ingredient in rocks such as limestone, chalk, and marble
- When calcium carbonate decomposes, it forms oxide of calcium called lime
Magnesium· Abundant element, formed into almost any shape
· Alloy of magnesium with aluminum and zinc are lighter than steel but just as strong
· Bike frames and “mag” wheels are made of magnesium
· The oxide of magnesium has such a high boiling point it is used to line furnaces
· Plants can’t function without it (chlorophyll)
· Plays key role in muscle function and metabolism
· Hard water = lots of magnesium and calcium ions
· Water softness exchange sodium or hydrogen ions for the calcium and magnesium ions
A) Arsenic, Antimony, and Bismuth (Group 5A)
· Group 5A
· Among the oldest know elements
· Arsenic is used for some illnesses
· Antimony used for common cosmetics (darkening eyebrows)
· Bismuth used as remedy for diarrhea and nausea
B) The Oxygen Group (Group 6A)
· Have 6 valence electrons and act mainly as nonmetals
· Tend to gain two electrons to form ions with a 2- charge
1) Oxygen:
· Joseph Priestley (1733-1804) is credited for the discovery of oxygen
· Oxygen has two allotropes (allotropes: Forms of an element with different structures and properties when they are in the same state-solid, liquid, or gas)
· Oxygen is separated from the other gases in air through a distillation process that is based on difference in boiling point among the gases
· Oxygen is the most abundant element in Earth’s crust
2) Sulfur:
· Found in underground deposits
· Has 10 allotropes
· Reacts with oxygen when burned in air to form sulfur dioxide, which is used to preserve fruit and as an antibacterial agent
· More than 90% of the sulfur dioxide produce is use to make sulfuric acid
· Heat and hydrogen sulfide released to deep ocean vents support many organisms
3) Selenium:
· Selenium can be found in suck foods as fish, eggs, and grains
· Selenium works with vitamin E to prevent cell damage
· Selenium can convert light into energy, so it can be used for solar panels
8A: Noble gases
Helium
Neon
Argon and krypton
7.3
Long-lasting lithium batteries may extend the ranger of electric automobiles. Compounds of lithium are used in dehumidifiers to absorb water. Lithium carbonate is used to strengthen glass and as a drug to treat bipolar disorders.
Alloys of lithium, magnesium, and aluminum are used for items such as airplane parts because these parts must be strong, yet lightweight. Alloy is used as a solid solution. A chemist can fine-tune the properties of an alloy by varying the amount of each element.
Sodium and Potassium
The most abundant alkali metals
Potassium is more reactive than sodium and more expensive to produce.
Humans and other vertebrates must have sodium and potassium in their diets because many biological functions are controlled by sodium and potassium ions.
When a nerve cell is stimulated, sodium flows in and potassium flows out. This flow of ions across the cell membrane carries the nerve impulse along the cell. After the impulse passes, a compound attached to the cell membrane uses energy to move the ions back across the membrane so that they are in position for the next impulse.
Other Alkali Metals
The most reactive alkali metals-rubidium, cesium, and francium-have little commercial use.
· Share properties such as electrical conductivity, luster, and malleability with other metals
· Little variation in atomic size, electronegativity, and ionization energy across period
· There are differences in properties, especially physical
· Physical properties determined by electron configuration
· Most transition metals are hard solids, with high melting points and boiling points
· Differences in properties based on ability of unpaired d electrons to move up into the next valence level
· More unpaired electrons in d sublevel the greater the hardness and higher melting points and boiling points of metal
Formation of Ions
· An ion is formed when an atom loses or gains an electron
· Losing electrons results in a positive charge
· Gaining electrons results in a negative charge
· Positive ions can have a charge of up to 6+
· Most compounds of transition metals have colour.
o The metal ions in these compounds have partially filled d sublevels
o Electrons in these sublevels can absorb visible light of specific wavelengths
o Exceptions are white compounds that contain scandium, titanium, or zinc
o Scandium and titanium ions have empty d sublevels
o Zinc ion has a completely filled and stable d sublevel
o Electrons in these three ions can be excited to higher levels, but not by visible light
o These compounds respond to wavelengths in the ultraviolet range
· If a transition metal can form more than one type of ion, a change from one to another can often be detected by a colour change
Sources of Transition Metals
Copper, silver, gold, platinum, and palladium are the only transition metals that are unreactive enough to be found, pure, in nature.
The rest of the transition metals are found in nature combined with nonmetals, usually in oxides, sulfides, or with other minerals in ores.
Copper, as it is found in nature.
Metallurgy is the branch of science that works with extracting metals from ores.
There are three groups of methods for metallurgy:
· Those that use high temperatures
· Those that use solutions
· Those that use electricity
Many countries’ economies rely on their source of transition metals. Places with an abundance of useful transition metals include Canada, Zaire, Democratic Republic of the Congo, and South Africa.
Magnetism & Metals:
· Magnetism is the ability of a substance to be affected by a magnetic field. A moving electron creates a magnetic field.
o Because paired electrons spin in opposite directions, their magnetic fields tend to cancel out. When all electrons in an atoms or ions are paired with another electron, the substance is slightly affected, if affected at all.
This property is called diamagnetism.
o When there is an unpaired electron in the valence orbital of an atom or ion, the electron is attracted to a magnetic field.
§ This property is called paramagnetism.
o Most substances act as temporary magnets: meaning their magnetic properties disappear after the magnetic field is removed.
o Transition Metals iron, cobalt, and nickel have a property called ferromagnetism. Ferromagnetism is the strong attraction of a substance to a magnetic field. The ions align themselves in the direction of the field. When the field is removed, the ions stay aligned and the metals continue to act as a magnet. Thus, iron, cobalt, and nickel can form permanent magnets.
Uses of Transition Metals
· Copper is used in electrical wiring.
· Zinc is used as protective coating for other metals.
· Iron is used in making steel.
· Many are found in alloys which are used to make things such as engines, drill bits, surgical instruments, and armor.
· Plastics, petroleum, and food industries use transition metals such as platinum, palladium, and nickel to control the conditions at which a reaction will occur.
· Our bodies need large amounts of some elements to function: carbon, oxygen, hydrogen, nitrogen, sulfur, phosphorus, sodium, potassium, calcium, magnesium, and chlorine. There are other essential elements, but only in small amounts.
· Except for scandium and titanium, all period 4 transition metals play vital roles in organisms.
· Iron (ions), Manganese, copper, and cobalt all help in some way with cells.
Halogens (Group 7A)
Halogens are a series of nonmetal elements from group 17 on the periodic table. This group includes flourine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). There is also a “undiscovered” element (ununseptium) that might also be a halogen.
Halogens are highly reactive. In sufficient amounts, they can be harmful/lethal to biological organisms. The reason why they are so highly reactive is because their atoms outer shells are one atom short of 8 electrons. Through reacting with other elements they can gain the electron that they need to have a full 8.
Bromine and chlorine are used as disinfectants to kill bacteria and other harmful microorganisms. If you were to fall and scrape your knee and need to clean it off, that’s what you would really be using. They are also used to disinfect our drinking water, swimming pools, dishes, and surfaces. Chlorine is used to bleach paper products and fabrics.
-Named for their ability to form compounds with almost all metals.
-Because these compounds are called salts, the elements are called “salt formers” or halogens.
-Halogens differ in their physical properties.
-Chemical behavior is similar with only one exception. Astatine is a radioactive element with no known uses.
-The elements share the following general properties:
-reactive non-metals
-always found combined with other elements in nature
-have 7 valence electrons
-generally forms ions with a 1- charge
Fluorine
-Halogen with the lowest atomic number, so it has a small atom that provides little shielding of its valence electrons from the nucleus.
-Most electronegative element on the periodic table. It has the greatest tendency to attract electrons. Also the most active element
-Reacts with every element except helium, neon, and argon.
-The mineral fluorite, which contains fluoride and calcium, is used to lower the melting points of other minerals to make it easier to separate them from their ores.
-Fluorine compounds are added to toothpaste and drinking water to protect tooth enamel from decay.
-A compound of fluorine and carbon provides a non-stick coating on pots and pans.
Chlorine
-Reacts with nearly all elements.
-Chlorine is a deadly gas, but it has many uses, some which save lives.
-Chlorine compounds are used as bleaching agents by textile and paper industries.
-Hydrochloric acid in your stomach helps digest food.
Bromine and Iodine
-Few commercial uses for their compounds.
-Your body needs iodine to maintain a healthy thyroid gland. This gland produces hormones the control growth and your metabolic rate.
-Seafood is a good source of iodine.
-Campers use iodine to disinfect water.
There are five known halogens bromine, idodine, chlorine, flourine, and astatine.
Halogens are non-metallic elements found in group 17. They are highly reactive, and only found as compounds or ions.
At room temperature fluorine and chlorine are gases, bromine is a liquid and iodine and astatine are solids.
Noble Gases
Among the last naturally occurring elements to be discovered because they are colorless and unreactive.
Known for their stability
Have maximum number of electrons in their outermost energy level.
Helium
Lightest Noble Gas.
Found on earth in natural gas wells.
Used in blimps, airships, and balloons.
Liquid helium is used as a coolant for superconducting magnets.
Neon
Used in light displays that are commonly referred to as neon lights
Color of neon lights is not constant because gases other than neon can be used in the displays.
Argon and Krypton
Argon is most abundant of the noble gases on Earth, makes up about 1% of Earth’s atmosphere.
Provides an inert atmosphere for procedures such as high-temperature welding.
Both used to prolong the life of filaments in incandescent light bulbs and as a layer of insulation between panels of gas.
Inner Transition Metals
Lanthanide Series
Silvery Metals
High Melting Points
Very little variation between two elements in the series they are found mixed together and are very hard to separate.
Actinide Series
Radioactive elements
Only three exist in nature, the rest are synthetic elements called transuranium elements, an element with an atomic number greater that 92.
Transuranium elements are created in partial accelerators or nuclear reactor.
Most decay quickly; one exception is plutonium-239 that can stay radioactive for thousands of years.
Group 3A: The Boron Group
*Group 3A elements are always found combined with other elements in nature
*Most often found as oxides in Earth's crust
*Group 3A contains one metalloid (boron), one metal (aluminum), and three rare metals (gallium, indium, and thallium)
Boron
+Boron is one of the seven micronutrients essential to all plant growth
+used in reactor control rods
+melting point: 205°C+Main Source of Boron is a complex compound of boron called "borax"
+Half of the world's supply of borax comes from a large deposit in California's Mojabe Desert.
+Borax is used as a cleaning agent and as fireproof insulation
+Boric acid is another compound of boron and is used as a disinfectant and as an eye wash
+Boron Nitride is the second hardest known material
Aluminum
+Aluminum is the most abundant metal and third most abundant resource in the earth's crust
+Aluminum oxide is the major compund in bauxite
+ The compud aluminum sulfate, known as alum, is used in antiperspirants and to remove supended particles during water purification
Gallium
+Gallium is used in some thermometers because it remains a liquid over a wide temperature range : 30°C to 2403 °C
+ A compound of gallium and arsenic called gallium arsenide produces and electric current when it absorbs light
Group 2A: Alkaline Earth Metals
· Group 2A elements form compounds with oxygen called oxides
· Oxides produce alkaline solutions when they react with water
· Alkaline earth metals are shiny solids that are harder than alkali metals
· Alkaline earth metals are usually found combined with oxygen and other nonmetals in Earth’s crust
· When exposed to oxygen, they form a thin oxide coating
Beryllium
- Lightest member of Group 2A
- Is found combined with aluminum, silicon, and oxygen in a material called beryl
- Used to moderate neutrons in nuclear reactors
- Tools made from an alloy of beryllium and copper are used in situations where a spark from steel tools touching steel equipment could cause a fire or explosion
Calcium- Essential element for humans in maintaining healthy bones and teeth
- Mainly combined with carbon and oxygen in calcium carbonate
- Main ingredient in rocks such as limestone, chalk, and marble
- When calcium carbonate decomposes, it forms oxide of calcium called lime
Magnesium· Abundant element, formed into almost any shape
· Alloy of magnesium with aluminum and zinc are lighter than steel but just as strong
· Bike frames and “mag” wheels are made of magnesium
· The oxide of magnesium has such a high boiling point it is used to line furnaces
· Plants can’t function without it (chlorophyll)
· Plays key role in muscle function and metabolism
· Hard water = lots of magnesium and calcium ions
· Water softness exchange sodium or hydrogen ions for the calcium and magnesium ions
7.3 Properties of d-Block and f-Block Elements
Vocabulary
Lanthanide series- The f-block elements that form period 6.
Actinide series- The f-block elements from period 7 that follow the element actinium.
Ferromagnetism- The strong attraction of a substance to a magnetic field.
Metallurgy- The branch of applied science that studies and designs methods for extracting metal and their compounds from ores.
Magnetism- The ability of a substance to be affected by a magnetic field.
Diamagnetism- When electrons repel or are unaffected by a magnetic field.
Paramagnetism- When an electron is attracted to a magnetic field
• Transitional metals vary in atomic size, electro-negativity and ionization across the period. Although they share like qualities, they have many differences in properties, such as structure and strength.
• Differences in properties are among transition metals are based on the ability of unpaired d electrons to move into the valence level.
• The D- block transition metals and f-block inner transition metals are more similar across a period than are the s-block and p-block elements
• The more unpaired electrons in the d-sublevel, the harder the transition metal and the higher its melting point and boiling points.
• In ferromagnetic metals, ions are permanently aligned in the direction of a magnetic field.
• Many transition metals are strategic metals.
• Lanthanide are silvery metals with high melting points such as: tinted sun glasses.
• Actinides are radioactive elements such as: americium which is found in smoke detectors.